Telephonic subscriber lines today are increasingly employing all-digital networks for both voice and data transmission so as to provide the utmost in signal integrity and flexibility inherent in digital networks. Further benefits accorded to the subscriber include the more efficient provision of existing and new services, such as telephony, packet- and circuit-switched data, telemetry, electronic mail, alarm signaling, telex, facsimile, and banking transactions over the same medium, thereby greatly reducing equipment and space requirements. Additionally, benefits accrue to the telephone company in terms of increased revenue derived from the provision of these new services, and simplified management resulting from all services operating on a single (digital) network.
To provide an interface to such all-digital voice/data networks on the subscriber's premises, the prior art has employed discrete and/or expensive custom circuitry which lacks the flexibility to meet changing subscriber needs. Furthermore such circuitry encourages proliferation of incompatible implementations which vary in physical, electrical and line protocol characteristics. Additionally, the prior art interfaces occupy large amounts of space, have high power consumption thereby generating considerable heat which requires cooling apparatus and lack the reliability of monolithic integrated circuitry.